The commonly used portable cards, such as financial cards, credit cards, stored-value cards, easy cards, health insurance IC cards, citizen digital certificates and so on, can be divided into contact cards and contactless cards according to the manner in which the cards are used. A contact card has a security chip exposed from the card surface for electrical contacting with an external card reader, so that the card reader can read required data from the security chip to perform a transaction with the card. On the other hand, a contactless card has an induction coil and a unique radio-frequency identification (RFID) tag embedded therein. When a user approaches the contactless card to a read module, an electromagnetic induction occurs between an antenna of the read module and the induction coil in the contactless card to produce induced electric current, allowing the read module to read data in the RFID tag for performing a required transaction.
However, the conventional contactless cards or contact cards do not include any system for providing a notice to a consumer, and the consumer can usually be informed by the store whether a transaction has been completed without the possibility of knowing the transaction state directly from the card being used. Therefore, the consumer's personal and transaction data in the RFID tag are subjected to the risk of being stolen by a malicious store using some kind of machine during or after the transaction.
It is therefore tried by the inventor to improve the prior art portable cards by developing a portable card with transaction display function, which is able to output a transaction message as a notice during a transaction using the portable card.